Party line identification dial



Jan. 8, 1952 g g 2,581,689

' PARTY LINE IDENTIFICATION DIAL Filed April 10, 1950 3 Sheets-Sheet 1 INVENTOR.

LEN B. MITCHELL ATTORNEY Jan; 1952 L B. MITCHEI;L 0 2,581,689

PARTY LINE IDENTIFICATION DIAL Filed April 10, 1950 3 Sheets-Sheet 2 66' SUBSTATION 304 FIG 3 PARTY LINE SWITCH 320,

m- J c|3| MEMOS 332 :1 L

I02 1 R340 |0| (I07 I I03 I I 333 I l c 32 334 l 322 I M308 Mae 3 If [:zl sex sue. 314

M308 -M3|s 33msua. 302 33-sua 3|2 M305 "M3l5 ISMSUB. 30| 5:] IGNSUB. 3||

INVENTOR. LEN B. MITCHELL ATTORNEY Jan. 8, 1952 L. B. MITCHELL PARTY LINE IDENTIFICATION DIAL 3 Sheets-Sheet 3 Filed April 10, 1950 2 1&1 O 3 6 6 6 w M 4 4 4 C C R w w I. .I l l l l II lll- |..ll|.|||llll|l .1 a w 6 4 4 m l I I I l I 5 44 w l I I l l l I I I I I ll 4 m w R J 4 W R A P K E R I m m 2 J 4 4 mq v-A I l llmTlv. m4 4 4 m o 4 O 7 l 2 4 M 4 4 \l \I all h 3 5 M m m m m M C F C C C C TO INDIVIDUAL MANUAL- I OPERATOR REPEATER SELECTOR 405 SPECIAL SERVICE SELECTOR CONNECTORS TOLL 50" PARTY CONN.

CONN. 404

66 PARTY ,INVENTOR. LEN B. MITCHELL a ATTORNEY Patented jam. 8,

a corporation of Delaware matic Electric Laboratories, Inc., Chicago, 111.;

Application April 10, 1950, Serial No. 155,093'

4 Claims.

The present invention relates to telephone systems and more particularly to improved calling devices which are adapted for identifying calling stations on party lines. in automatic telephone systems of the measured service type. The improved calling device is adapted to b used in a measured service system of the type disclosed in Ostline Patent 2,366,647, which issued Accordingly, it is an object of this invention to provide in a measured service telephone system an,

improved arrangement for identifying the particular calling station on a party line..

. A further object ofthe invention is to provide an improved calling device which is of simple and compact construction and which is difiicult to get.

out of adjustment under normal operating conditions. I

A further object of the invention is to provide an improved calling device in which two impulse senders are always maintained in proper synchronization.

These and other objects are accomplished in accordance with this invention by mechanically.

relating the operation of oneimpulse sender to the operation of another impulse sender.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operatiornto-j gether with further objects and advantages thereof, will best be understood by reference-to the following specification taken in connection with the accompanying drawings, in which Fig. l is a rear view of a calling device embodying the present invention; Fig. 2 is a side elevational viewof the calling device shown in Fig. 1; and Figs 3 and 4 taken together illustrate diagrammatically a telephone system embodying the present invention.

Referring now more particularly to Figs. 1 and 2 of the drawings, there is shown a calling device IIJ of the finger dial type and of the general con struction andarrange ment of that disclosed in a 2 U. S. Patent No. 1,642,822, Herbert F. Obergfell, granted September 20, 1927, which has been modified to embody the present invention.

More particularly, the calling device It comprises a ca II, a rotatable arbor I2, a finger wheel or dial I3 secured to an enlarged boss I4 provided on they outer end of the arbor I2, and a cooperating finger stop I5. The finger wheel I3 has ten spaced-apart openings therein, not shown, which are adapted to receive the finger of the user and which respectively correspond to the digits 1 to 0, inclusive. Also a coil spring I6 is provided in surrounding relation with respect to the arb0r;I2 ,'the ,inner end of the coil spring being secured to the casing I I and the outer end thereof being secured to the outer end of the arbor I2. The rear wall of the casing II carries a bracket Il, the bracket being secured in place by two spaced-apart screws I8. The bracket I1 carries a set of impulse springs I9 and 20, a set of shunt springs H, 22 and 23, and a set of cam springs 24 and 25.

In order for the identification pulses to operate properly the cam springs 2d and 25 must make contact a moment after the impulse springs I9 and 26 and must break contact a moment before. Inorder to insure that the cam springs 24 and 25 are properly timed with respect to the impulse springs I9 and 20 their operation is made to de-.

pend upon a spacer 25a between the impulse spring I9 and cam spring 25. When the impulse spring I9 is actuated the spacer 25a moves the cam spring 25 in unison therewith in a manner to be more fully explained hereinafter.

The inner ends of the impulse springs I9 and 2!] are suitably insulated from each other and from the bracket Il by a plurality of strips of insulating material 26 and are retained in clamped position by two screws 21. impulse springs I9 and 2|] are respectively provided with electrical terminals 28 and 29. Similarly, the inner ends of the shunt springs 2|, 22 and 23 are suitably insulated from each other and from the bracket I1 by a plurality of strips of insulating material 36 and are retained in clamped position by two screws 3|. .Also, the shunt springs 2|, 22 and 23 are respectively provided with electrical terminals 32, 33 and 34. Finally, the innerendsof the cam springs 24 and 25 aresuitably insulated from each other and from the bracket IT by; certain of the strips of insulating material 26 and are retained in clamped position by the two screws 21. The electrical terminal 33 is common to the shunt spring 22 and the cam spring 24; while the cam Also, the

spring 25 is provided with an electrical terminal The peripheral edge of the cam 4| has a projection 45 which is of varying length depending upon the identity of the subscriber. The impulse spring 20 carries an insulating control member 46 which cooperates with the control arm 43; and the shunt spring 23 carries an insulating control member 41 whichcooperates withthe control arm44.

Further, the calling device l comprises mechanism, not shown, housed in the casing II, which includes a gear train and a-connectedrimpulse spindle 48 extending through an opening Ha provided in the rear wall-of the-casingJI.

The outer end of the impulse spindle-48 carries an impulse cam 49 which cooperates with the extreme outer end of the impulsespring J9.

When the finger dial l3 occupies its normal position the arbor I2 is biased in a clockwise direction, as viewed in Fig. 1, by the coil spring l6; whereby the control arm 43 carried' by the fixture 40 engages the control member 4$ in order to urge the impulse'springs |9and 20 into engagement, and the control arm'44 carried by the fixture 40 engages the control member 41 in order to urge the shunt springs 2|, 22 4-.and :23 into'diseng'agement. At this point it is noted that the shunt spring 23 is normally biased toward theshunt spring 22 dueto its own resiliency. Also,the projection 45 carried by the' cam 4| is disposed forwardly in a clockwise direction with respect to the outer end of the pawl38; and the pawl 38 is biased in'a counterclockwise direction about the pivot pin '31- by the leaf spring 39.

In order to operate the-calling device 19, the user'inserts his finger into one of the holes provided in the finger wheel 13 corresponding to the digit to be transmitted and rotates the finger wheel l3 in a counterclockwise direction, as ,viewed in Fig. 1, until his finger engages the finger stop I5 and then releases the finger wheel l3; When the finger wheel l3 and the arbor l2 secured thereto are rotated in a counterclockwise direction, the coil spring [6 -is wound and the mechanism housed in the casing is set to transmit the digit thus registered. 'More particularly, when the arbor |2 iszrotated in a counterclockwise direction the control arm' 43 carried'by the fixture 40 disengages the control member 46, thereby to allow the impulse springs I9 and 20 to move, while maintaining engagement therebetween, toward and into cooperating relationship with respect to the impulse cam 49; however, the impulse spindle 48 andthe impulse cam 49 carried thereby are not rotated prior to the release of the finger wheel t3. Also, when the arbor I2 is rotated in the-counterclockwise direction the control arm 44 carried by the fixture 40 disengages the controlmemberfl, whereby the shunt spring 23 is moved into'engagement with the shunt spring 22- and forces the shunt spring 22 into engagement with the shuntspring 2| due to the inherent-resiliency of the shunt spring 23, as previously noted. Finally, as the arbor |2 is rotated in the counterclockwise direction, the projection 45-carried 'on'the periphery of thecam 4| rides over the 4 moved into engagement with the cam spring 25 due to this action of thepawl 38. When the projection 45 carried on the periphery of the cam 4| rides over the outer end of the pawl 38 and therebehind, the leaf spring 39 pivots the pawl 38 in the counterclockwise direction about the pivot pin 3'! back into its normal position,

without moving the cam spring" 24 into engagement with" the cam spring-25.

At this time, when the finger wheel I3 is re- -'-leased it is returned in the clockwise direction -.;as viewed in Fig.- 1, by the coil spring it back into its normal position, whereupon the mechanism' housed in the casing rotates the impulse spindle'48;an-appropriate amount corresponding *tothe digit-registered. At this time, the outer end of ,the impulse.; spring I9 is arranged in copulse cam 49 due to the disengagement between the control arm 43 carried by the fixture 40 and the control member 46 carried by ;the impulse spring :20; accordingly, .each timean end ofathe cam 49 engages the outer end of the impulse spring :19 the impulse spring I9 is movedlout of engagement with .the impulse spring29. Hence. the opposite ends of the impulse cam 43 alternately engage and. disengage the outer end :of the impulse spring 19, thereby alternately to move the impulse spring |9 into disengagement and topermit it tobe returned-into engagement with the impulse spring 20, ,whereby the callin device [0 transmits-a number ,of. impulses by way of the impulsesprings l9 :and 20;corresponding to the. digit registered.

Also, when thefingenwheel I3 is released the cam 4 carried .on the outer end of 1 the. arbor t2 is rotated in..a clockwise direction, .as-viewed ain Fig. 1,:whereby ,the projection 45 carried on the peripheryof .the cam-4| engages the outer end of the pawl 38. More particularly, vwhen'rthe projection :45 carried on the :-periphery of the cam 4| engages the rear surface of the outer end of .thepawls38 the pawl: '38 is urged .inl-va counterclockwise direction about the pivot pin 31, .as: viewed fin Fig.':1;*however, movement of the pawl 38 in the counterclockwise direction about the -pivot' -pin 91 is blocked due to thearrangement of the pivotal mounting-of the pawl 38 upon the cam spring 24. Accordingly, at this time the pawl 38 J is forced I outwardly and downwardlyaway from --=the engaged projection 45 carried on the periphery of-the cam-4 in order to force the cam spring 24 into engagement with the cam 'spring 25. Subsequently, when the-projection- 45 'carried--on the periphery of the cam 4| rides-over the-outer ends of the pawl 98, the pawl 38 andthe cam spring 24 are returned to their normal position due'to the inherent resiliency-of-the cam spring "24, whereby the cam spring -24 --moved into disengagement with the camspring*25. Accordingly, as the arbor i2 is rotate'd in the-clockwisedirection back into its normalposition the projection 45 on'the peripheryof'the-cam 4| causes-the camsprings-24 and 25 -tooperate into-engagement and disengagement-alike number of times, whereby the calling device l0 transmits a-number of impulses by-wayof the-cam'springs-24 and25 corresponding to thelengthof the projection '45 provided onthe periphery of 'thecam 4|.

The cam spring 24 is adjusted so that it makes V contactwith-impulse spring'25. only when projection- 45 engages cam 38' and cam spring |19,engages'cam49. "By a'olose'adjustment ofv cam spring 24'itis possible to havetheimpulse'springs 24 and 25 break just an instant before impulse springs I9 and 29 as the cam 49 rotates. This operation may be followed by reference to Fig. 1. The windup of the finger wheel I3 will rotate the cam 4| in a, counterclockwise direction. During this operation the pawl 38 will rotate as the projection 45 passes over it and the impulse springs 24 and 25 wil remain stationary.

On the return of the finger wheel I3 the cams 4| and 49 will both rotate. The cam spring I9 will be given a back and forth motion by alternate engagement and disengagement with the cam 49. Prior to the time that projection 45 engages pawl 33 this action will alternately make and break impulse springs I9 and 29. The presence of the spacer 25a, which may be fastened either to spring I9 or spring 25, results in a back and forth motion being imparted to impulse spring 25 but no contact is made between impulse springs 24 and 25 until the projection 45 engages the pawl 39.

As soon as the projection 45 engages the pawl 38 the cam spring 24 is advanced toward the impulse spring 25. The continued rotation of the cam 49 then effects contact between the impulse springs 24 and 25 during instants that the cam 49 does not engage the cam spring I9. As soon as the cam 49 engages the cam spring I9 contact beween impulse springs 24 and 25 is broken.

The apparatus is so adjusted that with the projection 45 in engagement with the pawl 39 the distance between impulse springs 24 and 25 is slightly greater than the distance between impulse springs I9 and 29. This insures that contact between the impulse springs I9 and 29 'will be made a short time interval before contact is made between the impulse springs 24 and 25. It also insures that'contact between the impulse springs 24 and 25 will be broken a, short time interval before contact is broken between the impulse springs I9 and 29. The total number of contacts made between the impulse springs 24 and 25 may be increased by increasing the peripheral length of the projection 45. On a four-party line the individual parties may be identified either by omitting the projection 45 or else having it of sufficient length to close the impulse springs one, two, or three times during the return travel of the finger wheel I3.

Just prior to the time the arbor I2 is rotated in the clockwise direction completely back into its normal position, the control arm 43 carried by the fixture 49 engages the control member 46 carried by the impulse spring 29 and forces the impulse spring 29 away from the impulse cam 49, whereby the outer end of the impulse spring I9 is forced out of cooperating relationship with respect to the impulse cam 49 in order to prevent any further operation of the impulse cam 49 from operating the impulse spring I9. Ultimately, when the arbor I2 is rotated in the clockwise direction into its final normal position, the control arm 44 carried by the fixture 49 engages the :control member 41 carried by the shunt spring 23; whereby the shunt spring 23 is forced out of engagement with the shunt spring 22 and the shunt spring 22 is forced out of engagement with the shunt spring 2 I, due to its inherent resiliency. Also, when the arbor I2 has been rotated in the clockwise direction to its final normal position, the projection 45 carried on the periphery of the cam 4| has operated the associated pawl 33, in the manner explained above.

At this point, it is noted that the arrangement of the control arm 43 carried by the fixture 49 and the control member 46 carried b the im pulse spring 29 is so coordinated with respect to the mechanism housed in the casing II that all of the digits registered in the mechanism have been transmitted by way of the impulse springs I9 and 29 a slight time interval prior to the final return of the finger wheel I3 and the connected arbor I2 into their normal positions. noted that the shunt springs 2|, 22 and 23 are moved into disengagement only upon the final return of the finger wheel I3 and theconnected arbor I2 into their normal positions; while the projection 45 provided on the periphery of the cam 4| operates the associated pawl 38 just prior to the final return of the finger wheel l3 and the connected arbor I2 into their normal positions. The cooperation between the elements mentioned positively insures that the shunt springs 2i, 22 and 23 are operated into engagement at all times when the finger wheel I3 is away from its normal position; while the finger wheel I3 must be moved a predetermined distance from its normal position in order to cause the first digit 1 to be effectively registered in the mechanism housed in the casing II. Also, the cooperation between the elements mentioned above permits control of the cam springs 24 and 25 to send one impulse in excess of the number of impulses in the digit registered in the mechanism housed in the casing II when the digits 1 and 2 are registered therein. By way of illus-' tration, it is pointed out that, in the present embodiment of the calling device I9, when the digit 2 is registered in the mechanism housed in the casing II, in order to cause the impulse springs I9 and 29 to be controlled to transmit two impulses, the cam springs 24 and 25 are controlled to transmit three impulses, projection 45 being provided on the periphery of the cam 4| with sufficient peripheral length to accomplish this. Further, it will be understood that the length of projection 45 may be varied as previously explained in order to obtain selective control of the associated switching apparatus; however, in the present embodiment it is contemplated that the cam 4| will have no projection 45 thereon or will have a projection of sufficient peripheral length to close the impulse springs 24 and 25 one, two, or three times, thereby rendering the calling device I9 capable of four modifications, in an obvious manner, as will be explained more fully in conjunction with the telephone system in which the calling device I9 is incorporated.

Referring now more particularly to Figs. 3 and 4 of the drawings, the telephone system there illustrated comprises an exchange having a plurality of individual subscriber lines, not shown, terminating thereat, and a plurality of party subscriber lines, including the party subscriber lines I29 and I39, terminating thereat, and provided with switching apparatus. Each of the party subscriber lines has four party subscriber substations individually associated therewith; the party subscriber substations 39I, 392, 393 and 394 being individually associated with the party subscriber line I39 and the party subscriber substations 3| I, 3I2, 3I3 and 3I4 being individually associated with the party subscriber line I29. Each party subscriber substation comprises substation apparatus, including a harmonic ringer, the four harmonic ringers at the four party subscriber substations on each party subscriber line being respectively tuned to 16, 33, 50 and 66 cycle ringing currents. In the present example,

the party subscriber substations 39I, 392, 393 andv Also, it is assesses 304i.;connected;;.to: the zpartyl subscriber, line? l 305. and the-eparty;subscribensubstations 3, M2,. 3l3g-and 314 connected to the. party-subscriber:

line s|20.'..are respectively.-v 16, 33,. 50. and. 66 cycle substations. 1

Preferably, the substation. .appa-ratussprovided;

at each; party. subscriber; substation is substan-.

party-subscriber line I30, with the exception. of

at, as :noted :more particularly below. The sub-.

stationapparatus provided at the fourth party;-

subscriber substation 394 comprises a harmonic ringer .101, a transmitter I02, a receiver I03, a.

hoolgswitchfiHi l an inductionzcoil- Hi1 and a.

calling device In, the calling device It! being identical to that disclosedin Figs. 1 and2 of the:

drawingsand including a cam 4| provided with a projection on its periphery. The substation apparatus provided at the first, second andthird. party -subscr,iber substations 36!, 302 and 383, respectively, is substantially identical to that provided at the fourth party subscriber substation 304-, except that in the calling devices respectively provided at these party subscriber substations, the cam 41 comprises no projection 45, or a projection .45 of sufficient length to give one, two, or three impulses. In-viewof the fact that the calling devices providedat the first party subscriber substations 3M; 3, etc., each comprise a cam 41 provided with no projection 45 therein, the. calling device provided at each first party subscriber substation may be of conventional construction and arrangement and of the and a plurality of party line switches,-including the party line switches 32!)..and360, individually associated with the. party subscriber lines, the line switches 32!} and 360 being respectively individually associated with the. party subscriber lines I35 and I20.. Also, thisswitching apparatus ,comprises aplurality of meter switches 35.0,

310,etc., individually associated with the party line switches 320,, 368,, etc., whichare, in turn,

individually associated with the party subscriber lines I3El,. I20, etc.. Further, this switching apparatus comprisesagrouphof regular selectors, not shown, a group of repeater selectors, including,the repeater selector 405, agroup ofspecial service selectors, including.- the special service selector 485, four groups of individual connectors, not shown, and four groups ofpartyconnectors.

The first, second, third, and. fourth... groups of. party connectors respectively include-theparty. connectors 401, 492;,4031and4t34, which. party. connectors respectively, ring a line seized thereby with 16, 33, and. 66 cycle ringing currents.

Further, the exchange comprisesv a manual op;-. erator position 0, a toll operator position. HG

and a plurality of measuredservicemeters indi vidually associated with the. party subscriber.

substations. More particularly, the meters M305,.

M336, M301 and M308 .are respectively individually associated with;.the.partysubscriber sub.- stations 30!", 302, 303.and 304; and the meters 8 dividually associated withgthe;rpartyi subscriber substations: 3 I] 3| 2,. 3 l3. and; 3 [4. Finallyrgthee:

exchange,. .comprises a: group... of; repeaters, ;.in.-:

cluding the. repeateri lllfl.

The apparatus intheaexchange issoconnected and arranged that eachof thenindividualline: switches, has .accesstothe group of; regular, S9711: lectors; while-each ofrthe party line switches:'32 8,:* 330, etc., has access 130368131101 the repeaters 400, etc., bylway, ofdncomingtrunks 410; etc., indi-v vidual .to .therepeaters, 40fl;;;etc. Each -repeater 400,l, etc., in;- the:g1t.0up; isdirectly connected by way of-an'outgoing trunk .480,-.etc., individual thereto to;.a corresponding oneeof the ,repeaterselectors ldietc in theassociated-group; Each;v

meter switch is individually associated with-one;- of the partyiine switches andhas access. tO.'thei--. four meters;- respectively individually asscciatedw with the four party subscriber substations con.

nected to the party subscriber; line With WhiChw the party line switch is individually associated..-. By wayof example, it isnoted that the meter switch..350 V is individually associated with. the party line switch 320.1-and has access to thefour ;meters M335, M306, M301 and M308-respectivelg individually associated with the founparty subs-- scriber substations 30!, 302,-: .303 and 3047 connected to the party subscriber line] 30withwhich. the party line :switch 320- is individually asso.: ciated.

Each of the regularselectors.in,the .group, and each of the repeater-selectorsin the groupthave. access tothe groupof special service selectors, to the four groups of party connectors, to .the=: four groups of individual-connectors,andtda... group of trunks extending; to .the manual opera ator position 0. Each ofthe individual connece tors in each of the .groups .has access-to each of-- the individual subscriber lines; each of. the party, connectorsin each oflthe groups has access tor each of the party subscriber linespand each oi; the special servicev selectors .in the group has-ace cessito a-group of trunksextending tothe .toll operator position. I I0.

Preferably, each of the individual lineswitches. is of conventional connection and arrangement;v while .each of the partyline switches is.identical.,. to. the-party line .switch....32il. v The party. lineswitch 326 comprises a switching mechanism, including arotary wiper. set provided with five wipers 32!, 322, 323,. 324 and. 325, an associated.v contact bank,v anda rotary magnet-M326 for driving the wiper set noted. Also, the party line switch .32ilcomprises. a. relay network. including. a cutofi relay R330 and a line relayREltfl.

Preferably, each of the meter switches is iden-.v

.tical to the. meter switch 356, which comprisesa.

switching mechanism includinga rotary wiper, set provided with a single. double-ended Wiper,

35L an associated contact bank, and a rotarymagnet M352 for. driving the wiper set noted.

Also, a set of switch springs S354 is associated with the. wiper set. of themeter switchjtel and operated, in a manner more fully'gexplained here-. inafter.

Preferably, each of the repeaters is identical to the repeater 4B9 which comprisesa relay network, including a digit cutofi relay R4lfija meter relay R420, a dial relay R430, an answer relay R44i!,'a line relay R450, a hold relay R438 and an impedance element 4l5.

Preferably, each of the regular selectors and each of the repeater selectors 495,. etc.,. are of the conventional.Strowgertype; ,each. of the in :dividualconnectors'and'each of the party con nectors 40 I, etc., are of the conventional Strowger type; each of the special service selectors 400, etc., is of the conventional drop-back Strowger type; and the manual operator position and the toll operator position IIO comprise conventional operator position equipment.

In accordance with the trunking plan incorporated in the telephone system, -both the regular selectors and the repeater selectors have access to the group of special service selectors in the first level of the associated contact banks, to the first, second, third and fourth groups of party connectors in the respective second, third, fourth and fifth levels of the associated contact banks, to the four groups of individual connectors in the sixth, seventh, eighth and ninth levels of the associated contact banks, and to the group of trunks extending to the manual operator position 0 in the tenth level of the associated contact banks. The connection and arrangement of the system will best be understood from a consideration of the following description, with reference to Figs. 3 and 4 of the drawings, of the operation of the apparatus incorporated therein to set up the different connections between the various individual and party subscriber substations.

Considering now the extension of a call from the fourth party subscriber substation 3M, connected to the party subscriber line I30, to the first party subscriber substation 3I I, connected to the party subscriber line I20, the call is first initiated at the four party subscriber substation 304 by removing the receiver I03 from its associated switchhook, thereby to operate the hook switch SIM. When the hook switch SIM is thus operated there is completed, at the contacts I05 and I06 thereof, obvious operative connections between the transmitter I02, the receiver I03 and the party subscriber line I30; whereby a circuit is completed for energizing the winding of the line relay R340 in the party line switch 320 individually associated with the party subscriber line I30. The circuit for energizing the winding of the line relay R340 extends from ground by way of the contacts 333, the line conductor CI32 of the party subscriber line I30, the primary winding of the induction coil I 01, the transmitter I02, the contacts I 05 of the hook switch SIM, the impulse springs I9 and 20 of the calling device I 0, the line conductor CI3I of the party subscriber line I30, the contacts 33! and the winding of R340 to battery.

When thus energized the line relay R340 operates to complete, at the contacts 342, an obvious path for applying ground potential to the control conductor C I 33 of the party subscriber line I30 in order to mark the party subscriber line I30 as busy to the party connector switches 40I, etc., having access thereto. Also, the line relay R34. completes, at the contacts 34I, an obvious test connection, including the contacts 335 and 321, between the control wiper 323 of the wiper set and the rotary magnet M323; and completes, at the contacts 342, anobvious ground connection to one terminal of the winding of the cutoff relay R330. At this point it is noted that the party line switch 320 is of the non-homing type, whereby the wiper set thereof engages an associated contact set at each step of the party line switch 320. Accordingly, at this time, the idle or busy condition of the incoming trunk terminated by the engaged contact set and extending to one of the repeaters is tested. In the event the lastmentioned trunk extends to a busy repeater,

ground potential appears upon the control conductor thereof and is applied to the control wiper 323 of the wiper set, thereby to complete a path, including the contacts 335, MI and 342, for shortcircuiting the winding of the cutoff relay R330, and to complete a low resistance circuit, including the contacts 335, SM and 321, for energizing the rotary magnet M326. When the rotary magnet M326 is thus energized it operates, thereby to condition the wiper set to be driven .one step in the rotary direction and to interrupt, at the contacts 321, the previously traced circuit .for energizing the rotary magnet M325. The rotary magnet M323 then restores, thereby to drive the wiper set one step in the rotary direction and to recomplete, at the contacts 321, the previously mentioned circuit, including the test wiper 323 of the wiper set, for testing the idle or busy condition of the trunk terminated by the contact set engaged by the wiper set at this time. On the other hand, in the event the wiper set engages a contact set terminating an idle trunk, no ground potential appears upon the control conductor thereof, whereby the previously traced test circuit, including the test wiper 323 and the rotary magnet M326, is not completed. Accordingly, the previously traced low resistance circuit for energizing the rotary magnet M326 is not completed and the previously traced path for shortcircuiting the winding of the cutoif relay R330 is not completed. Hence, when operation of the party line switch 320 is initiated the wiper set is driven a step in the rotary direction only in the event that it engages a contact set terminating a busy trunk, in which event the wiper set is driven step by step in the rotary direction until it engages a contact set terminating an idle trunk.

Assuming that the wiper set of the party line switch 320 engages the contact set terminating the trunk 410 extending to the repeater 400 and that the latter repeater is idle at this time, no

ground potential appears upon the control conductor C413 of the trunk 410. Accordingly, the previously traced low resistance circuit, including the control wiper 323, for energizing the rotary magnet M326 is not completed; and the previously traced path, including the control wiper 323, for short-circuiting the winding of the cut-- off relay R330 is not completed. Hence, at this time, an obvious circuit, including the contacts 342 and 321, is completed for energizing in series the winding of the cutoff relav R330 and the rotary magnet M326. When this series circuit is completed the cutoff relay R330 operates; however, the rotary magnet M326 does not op-' erate due to the high series resistance of the winding of the cutoif relay R330.

Upon operating, the cutoff relay R330 interrupts, at the contacts 33I and 333, the previously traced circuit for energizing the winding of the line relay R340, thereby to cause the 'latter relay to restore shortly thereafter, the line relay R340 being of the slow-to-release type. Also, the cutoff relay R330 completes, at the contacts 332 and 334, a circuit for energizing in series the upper winding of the line relay R450 and the upper and lower windings of the meter relay R420 in the repeater 400, this circuit extending from ground by way of the contacts 442, the lower winding of R420, the line conductor C412 of the-trunk 410, the line wiper 322, the contacts 334, the line conductor CI32 of the party subscriber line I30, the primary winding of the induction coil H", the transmitter I02, the contacts I05 of relay R330 1 and the rotary magnet M32 5. it*is noted that at this time ground'potential pacereas Eurther,.:the cutoftrelay R330 interrupts, at .tthercontacts3335, the previously traced :test cir- ..icuit :between -the'- 'control wiperu3z3 and the rotaryz-magnetMfl 6; and completes, at the: contacts 336;:anobvious path, including thecontacts -342 -and ithecontrol wiper 323. for app-lying ground potential to the 'control conductor 'C i'lfi of the'trunk d lllf thereby to mark the :trunk iill as busy to the other party line switches having accessthereto. Furthenthe cutoff--relay R333 -interru'pts,=-at -the contacts-33'I, a p-ointina homing circuit traced hereinafter for energizing the rotary magnet I M352 .of the meter switch 350; prepares, at' the: contacts'338y-a point in an operating circuit traced herein-after for-energizing the'rotary magnet M352 and prepares, -at' the contacts-339, a circuit traced'hereinafter "for Operatingthemeter M398 individually associatedwith the fourth party subscriber sub- -stat1on 304 connected to the party subscriber Uponoperating, theline relay R450 in the repeater 400 completesat the contacts 452, an obvious circuit for energizingthe'winding of the hold relayRASDf thereby to cause'the latter-g relay to operate. Uponoperatiil the holdrelay 12460 completes; at the contacts 45H, a loop' circuitextending between the repeater'Mlfi and the "repeater selector' '405 individually associated with 1 theifepeaterdflfl. )This loop'circuit extends from ""the'linegconductor 'C48i'0f the trunkft8il by.

"wayrot the contacts 4BI, the impedance M5, the left-hand winding of'the answerrelay RMG "and *themontacts 45I to the iine conductor "(3482M thetrunk 480; the line-conductors Cit I fian'd'Cd82 '"of the trunk 48!! being connected by -way of-the apparatus inthe repeaterselector -405 respectively to battery'andground potenttials wherebythe repeater selectori-fifiis con- -ditionecl to" be responsive to a'dig-it' transmitted:.1; thereto. When the repeat selector- 485 is=thus -conditioned-to--be responsive to'a digit trans- ;;mitted thereto, ground potential therein is applied tothe control conductorCdBS of'the trunk "48fl;-"and isreturned therefrom by way of the *control' conductor G473 of the trunk 4T0 to the controlwiper 323. This application-of ground potential to the control wiper- 323 completes an *Obvious"h01ding circuit for energizing in series the winding of thecutoff relay E3336 and the -rotary magnet M326 in "the party line switch F320. At-this point, it is notedthat the above- -mentioned holding eircuit is completed prior to {the restoration of the line-relay' RMEl in order itoyprevent the releaseof the -par-ty line switch "-320. Shortly after the above mentioned holding circuit -is completed the line rel'ay' R348 restores gin-orderto interrupt,-atthe contacts stl, a fur- -ther 'point in the previously mentioned testacirrouit, including the cont1'ol-wviper 323 and the --rotary -magnet M326; and to interrupt, at thecontacts 3 42,*the original operating circuit for -energizing in series-thgwinding of the cutoff Also,

:appearing; .upomthemontrol :conductor: 64.1 301' the trunk 4T0 'is returnedeby way: of..the control wiper "323 and :the lcontacts @336, :to the :ccntrol conductor .C'I 33;o:;the: party subscribenline l 38, thereby to retain therparty subscriber line I 30 marked as:busy-':toathe-1party 'connectorsetm,

'etc., having access thereto.

"Also, it is notedithatiwhen the previously traced loop circuit .betweenzthe-repeater 4fllbandcthezrepeater selector ADE-ids; completed, the leftehand winding of the answer.:relay;R440 =is energized;

' however, the latter: relay Hoesnottoperatezatthis time as the right hands-winding :thereofsisalso energized by way ofzan: obviousrcircuitpincluding the contacts 462;'which Wagccompleted:incidental to the operation :of :the :hold relay -Rtfifl. When both'the left-hand and tthe 'rightehanctwindings of the answer relay :Rdll: are thus: energized this "relay does not operates asrit: i of: the :polarized type. Accordingly, at this time an operativ'eiconnection is completedabetweenithe"fourth party subscriber substation' 3 fitgconnectedito the :party subscriber HD6130, :andtthe: repeater Why-way of the'party subscriber: line 7139,? the a-party 'llne switch32t and the trunk f410;'ia1so','athe repeater iiifl is operatively connected tofthezrepeaterc selector 405 by wayrofxtheftrunk 480. ixrFurther, dial tone current: is? returnedzfromthe repeater selector 4 05 by way of the? aboveetraced: connection to the'receiveri'i fl3z-rat-the.fourth'fpartyf subscriber-'substationztIl lizin orderctor indicate to' the subscriber :ithere'at thatzther'may :proceedto dial the first digit of the directorynurhber.

The 'subscriberiatthercalling:fourth'pen'ty subscriber substation 3Mxthenmroceeds :to dial "the first digit of the directory number :of ithen called firstparty:subscribertsubstation 31 I;lthe directory number of the"calledafirstzparty subscriber substation 3 I 'I :beingE2XX, 'suclmforieXample? 2.52234.

Whentthesubscriber atithezrcalling'sfourth party subscriber substation :304 :pu-lls the: finger: wheel of the calling device :10 accordance -Withfthe digit 2, the shunt springs 2 I 22 rand 231818 operated into engagement;,r'the.tmechanism housed in the casing of thercallingsdevice Jill registersthe digit 2; andthexcamidI-ds rotatedc-inra counterclockwise direction;zas'iviewedin Fig: 3, inrorder to move the projectionrfli carriedorrtheperiphery thereof:belrinda-therassociatedpawl- 38; in the manner-previously explained. "When the'shunt springs 2 I 22 and 23 ;are- :operated into engage- "ment, an obvious pathii's compl'eted'for shortcircuiting both the transmitter HlZ and lthe-re- 'ceiver fll3,'inaccordance' tvith conventional practice; *and a directcdialing :bridga'including'tthe primary :winding *ofrthe induction "'coil I ill, :the shunt springs 23-: and 22 -and theximpulse; springs "I9 and 120; is 'completedbetween-the lineiconiductors Ci32 and Ct3I":of-the'-"partysubscriber line I30.

'The subscriber at zthe:calling.fourthipartysub scriber substationrfiM' *'-then releases ithe finger wheel of the callingrlevice I n wherebythe'calling: device 'I 0 operates; inxthermanner: previously explained, in 'conjunctiomwithF-igs; 1' and '2 of. the drawings. *More particularly, the zcam'springs 24 and 25 operate*to"'transmit' a first grouridiimpulse cover the line :tcon'ductors TCIISILrand-QCIM --o'f -the'-party subscriberdine'i'IiBIi priQr to the operation of: the-impulsevsprings' I Stand-20 interrupt the previously trace'da loop icircuitztextending between the calling fourth rpartyr subscriberrsubstation 304 and 'the' repeater y HllLxin the manner previously explained. .The-ripathdor applying ground potential to theil-ine conductor -'CI.'3I ex- '13 tends from ground by Way of the cam springs 25 and 24, the shunt spring 22 and the impulse springs l9 and to the line conductor Cl3l; while the path for applying ground potential to the line conductor Cl32 extends from ground by way of the cam springs and 24, the shunt springs 22 and 23 and the primary winding of the induction coil l0? to the line conductor Ci32. The application of ground potential to the line conductor C|3l of the party subscriber line I completes an alternative circuit substantially identical to that previously traced for energizing in series the upper winding of the meter relay R420 andthe upper winding of the line relay R450 in the repeater 400; while the application of ground potential to the line conductor Cl32 of the party subscriber line I30 completes a path, including the contacts 334, the line wiper 322, the line conductor C472 of the trunk 4l0- and the contacts 442 for short-circuiting the lower winding of the meter relay R420. Accordingly, the line relay R450 remains in its operative position while the meter relay R420 operates, the latter relay being of the differential type and the lower winding thereof being short-circuited at this time. Upon operating, the meter relay R420 completes, at the contacts 42!, a circuit, including the contacts 4| I, the conductor C474 of the trunk 410, the wiper 324 and the contacts 338, for energizing the magnet M352 of the meter switch 350. When thus energized the magnet M352 operates in order to condition the wiper l to be driven one step in the clockwise direction away from its home position.

Upon complete operation of the cam springs 24' and 25 to transmit the first ground impulse, ground potential is removed from the line conductors Cl3l and Cl32 of the party subscriber line I30, whereby the previously traced path for short-circuiting the lower winding of the meter relay R420 is interrupted and the previously traced circuit for energizing in series thelower and upper windings of the meter relay R420 and the upper winding of the line relay R450 is recompleted. When both the upper and lower windings of the meter relay R420 are thus energized this relay restores as it is of the differential type, as previously noted; also, at this time the line relay R450 retains its operated position. Upon restoring, the meter relay R420 interrupts, at the contacts 42!, the previously traced circuitfor energizing the rotary magnet M352, thereby to cause the rotary magnet M352 to restore; whereupon the wiper 35! of the meter switch 350 is driven one step in the clockwise direction away from its home position.

The impulse springs 19 and 20 of the calling device [0 are then operated to transmit the first impulse, whereby the previously mentioned loop circuit extending between the calling fourth party subscriber substation 304 and the repeater 400 is interrupted and then recompleted, in an obvious manner. When the previously mentioned loop circuit is interrupted the series circuit for energizing the lower and upper windings of the meter relay R420 and the upper winding of the line relay R450 is interrupted, thereby to cause the meter relay R420 to retain its restored position and to cause the line relay R450 to restore. Subsequently, when the above-mentioned loop circuit is recompleted the previously traced series circuit for energizing the lower and upper windings of the meter relay R420 and the upper winding of the line relay R450 is recompleted, thereby to cause the meter relay R420 to retain 14 its restored position and to cause the line relay R450 to reoperate. Upon restoring, the line relay R450 interrupts, at the contacts 452, the previously mentioned circuit for energizing the winding of the hold relay R400; however, the latter relay does not restore at this time as it is of the slow-to-release type. Also, the line relay R450 completes, at the contacts 453, an obvious circuit, including the. contacts 463, for energizing the winding of the dial relay R430,

thereby to cause the latterrelay to operate.'

Upon operating, the dial relay R430 completes, at the contacts 43I, an obvious path for shortcircuiting the impedance element M5 and the left-hand winding of the answer relay R440, thereby to provide a low resistance bridge across the line conductors C40l and C482 of the trunk 480 and positively to prevent operation of the answer relay R440 incidental to switching surges impressed upon the trunk 400 incidental to operation of the repeater selector 405. Also, the dial relay R430 completes, at the contacts 433, an obvious circuit for energizing the upper winding of the digit cutoff relay R440. When the upper winding of the digit cutoff relay R410 is thus energized this relay takes a first step in order to complete, at the contacts 4l2, an ob vious path for short-circuiting the lower winding thereof. When the lower winding of the digit cutofi relay R4l0 is thus short-circuited it will not take a second step to interrupt, at the contacts 4! I, a prepared point in the previously traced circuit for energizing the rotary magnet M352 of the meter switch 350. Also, upon restoring, the line relay R450 interrupts, at the contacts 45!, the previously traced loop circuit extending between the repeater 400 and the repeater selector 405.

Upon reoperating, the line relay R450 recompletes, at the contacts 45!, the previously mentioned loop circuit extending between the repeater 400 and the repeater selector 405, recompletes, at the contacts 452, the previously mentioned circuit for energizing the winding of the hold relay R460, and interrupts, at the contacts 453, the previously traced circuit for energizing the winding of the dial relay R430; however, the dial relay R430 does not immediately restore as it is of the slow-to-release type, At this point, it is noted that neither the hold relay R400 nor the dial relay R430 restores during impulsing; both of these relays being of the slow-to-release type, as previously noted. The first restoration and reoperation of the line relay R450 is efiective to transmit an impulse over the trunk 400 to therepeater selector 405, thereby to cause the repeater selector 405 to take one step in the vertical direction, in an obvious.

manner.

During the subsequent operation of the calling device I0 the cam springs 24 and 25 operate to transmit their second ground impulse; then the impulse springs l9 and 20 operate to transmit their second impulse; and, finally, the cam springs 24- and 25 operate to transmit their third ground impulse; at which time the finger wheel of the calling device 10 is returned to its normal position and the first digit 2 has been transmitted therefrom. The second and third ground impulses transmitted by the cam springs 24 and 25 of the calling device l0 cause the meter relay R420 to operate and then restore two additional times; whereby the meter relay R420 is operated and then restored three times-incidental to the operation of the calling device I!) to transmit party connector dill, in an obvious manner.

abscess thewdigit 12', in the-.mannerv explained above.

This operation vof ,themeter relay R420 causes the wiper 351. of. the meter switch 1350 to .be advanced three-steps awayiro-m itsznormal positionin the clockwisedirectiomin the manner explained above, The second impulse, transmitted by the impulse springs l9 and of the calling device In causes the line relay 'R45ll'to restore :and reoperate. :one additional time; whereby the line relay R450 is restored and then reoperated twice incidental to the operation of the calling device ii! to transmit the digit 2, in the manner explained above. This-operation of the line relayRMill causes the digit 2 to be transmitted over the trunk 480-130 the repeater selector cs5, in the manner explained above.

Therepeater selector-465 responds to the first digit2 transmittedthereto to advance its wiper :set two-steps in the vertical direction; whereupon the wiper set thereof is operated auto- .matically in the rotary direction to select an idle party connector in thegroup, including the Assuming that the party connector "40! is seized :by the repeater selector 405, the party connector dot is then conditioned to be responsive to the second and third digits 3 and 4, respectively, in accordance with conventional practice.

. At'the conclusion of the first digit 2, the line relay Rfidreoperates, thereby to interrupt, at

lower winding of the digit cutoff relay RAH),

whereby an obvious circuit, including the contacts 484 and M2, is completed for energizing in series the upper and lower windings of the digit cutofi? relay RAH). When the above-traced circuit for energizing in series the upper and lower windings of the digit cutoii relayRdlB is completed, this relay takes a second step or'operates fully, thereby tointerrupt, at the contacts Ml, a further point the previously traced circuit for energizing the rotary magnet M352. At this time, the wiper 35l of the meter switch 358 has been operated three steps in the clockwise direction away from its normal position, thereby to prepare a circuit traced hereinafter foroperating the meter M368 individually associated with the fourth party subscriber substation 384 connected to the party subscriber line I30.

The subscriber at the calling party subscriber substation 395 then proceeds to dial the second digit 3, thereby ,to causethe line relay 'R45il to restore" and reoperate three timesin order to transmit the three impulses of the second digit over the trunk 48c and the repeater selector 895 to the .party. connector 110 i.

Ii) operates, in the manner explainedabove, in connection with the dialing of the first digit 2, whereby the meter relay R420 operates and restores three times. However,this operation of the meter. relay R428, incidental to thedialing Incidental to the dialing of the second digit 3, the calling device .16 conclusion of' the first digit 2 incidentalv ton-the restoration ofthe dial relay BASE, .in' the. man'- ner previously explained. Finally, thesubscriber at the calling party subscriber substation. 384 proceeds to dial the'third digit 4, thereby to cause theflline relay R456 to restore and reoperate four times in order to transmit the four impulses of the third digit over the trunk 489 and therepeater selector 405 to the party connector 40]. Also, incidental to the dialing of the third digit 4, the meter relay R4213 operates and restores three times however, this operation of the meter relayRAZfl is withou'tseiiect due to the fully operated position of the digit cutofi relay RMO. In 'view'of the foregoing explanation .of' the operationof the meter relay R428, incidental to the dialing of the second and third digits, it willbe nnderstood'that this relay is effective to control the setting of the meter switch 35b only. incidental to the dialing'of the first digit of the directory number, due to the full operation of the digit cutoff relay RMB at the conclusion of the first digit of "the directory number.

The party connector 40I responds to the second digit 3 andthe third digit 4 in accordance with conventional practicein order to seize theparty subscriber line I 20. Upon seizing the party subscriber line 20, the party connector 491 tests the idle or busy condition thereof; whereupon busy tone current is returned. over the repeater selector 495, the trunk 48!), therepeater dllll, the trunk 579, the party line "switch 3201 and the party subscriber line 13a to the calling fourth party subscriber substation 3M in the event the called party subscriber line no is busy at this time. On the other hand, in the event the called party subscriber line I26 is idle at this'time, the party connector 40! operates in order to return ring-back tone current over the previously traced connection to the calling fourth party subscribersu-bstation 304 connected to the party subscriber I respectively, connected-to the party subscriber I line I 20, are respectively tuned to ringing currents-having the respective frequencies of 33, 50 and66 cycles.

The subscriber at the called first party subscriber substation 3, connected to the party subscriber line i2li, answers the call by removing the'receiver of the telephone instrument thereat from its associated switchhook, thereby to complete an obvious operative connection, including the party subscriber line I29, between the first party subscriber substation 3i i and the party connector 4.9!. When this connection .is completed theparty connector it: operates in order to reverse battery over the repeater selector 405 and the loop circuit extending between the repeater selector 405 s and the repeater. 480.

When battery is thusreversed over the-abovementionedloop circuitthesleft-hand winding of theanswer relay R440 is energized in-the opposite direction, in an obvious manner, whereupon the answer relay R440 operates. Upon operating, the answer relay Rut-interrupts, at the contacts 442, the previously traced circuit for energizing in series the lower and upper windings of the meter relay R420 and the, upper winding of the line relay R450; and completes, at the contacts 44I, an obvious alternative, loop circuit for energizing in series the upper and lower windings of the meter relay R420 and the upper and lower windings of the line relay R450, whereby the loop. circuit extending between the fourth party subscriber substation 304, connected to the party subscriber line I30, and the repeater 400 is balanced in order to improve the transmission qualities thereof. Finally, the answer relay R440, upon operating, completes, at the contacts 443, a circuit including the conductor C415 of the trunk 410, the wiper 325 of the party line switch 320, the contacts 339 and the wiper 35I and engaged fourth contact in the associated contact bank of the meter switch 350 for operating the meter M308 individually associated with the fourth party subscriber substation 304, connected to the party subscriber line I30 in order to register the completion of a call from the last-mentioned party subscriber substation.

At this time, the previously traced loop circuit extending between the calling fourth party subscriber substation 304, connected to the party subscriber line I30, and the repeater 400 is completed; the previously traced loop circuit extending between the repeater 400 and the party connector MI is completed; and the previously mentioned connection extending between the called first party subscriber substation 3| I, connected to the party subscriber line I20, and the party connector MI is completed. Finally, it is noted that an operative connection between the trunk 410 incoming to the repeater 400, and the trunk 480 cut-going from the repeater 400, is completed by way of the condensers M3 and M4. Hence, an established connection is completed between the calling fourth party subscriber substation 304, connected to the party subscriber line I30, and the called first party subscriber substation 3| 2, connected to the party subscriber line I20, for two-way communication purposes.

The release of the established connection between the calling fourth party subscriber substation 304, connected to the party subscriber line I 30, and the called first party subscriber substation 3I I, connected to the party subscriber line I20, is primarily under the control of the subscriber at the calling fourth party subscriber substation 304, and is accomplished when the subscriber thereat replaces the receiver I03 upon its associated switchhook, thereby to operate the hook switch SI04. When the hook switch SI04 is thus operated the transmitter I02 and the receiver I03 are effectively disconnected froin the party subscriber line I30 and the previously traced loop circuit extending to the repeater 400 is interrupted, at the contacts I05 of the hook switch SI04, thereby to cause the line relay R450 in'the repeater 400to restore. Upon restoring, the line relay R450 interrupts, at the contacts 452, the previously mentioned circuit for energizing the winding of the hold relay R460, thereby to causethe latter relay to restore shortly thereafter. Also, the line relay R450 interrupts, at the contacts 45I, the previously traced loop circuit extending between the repeater 400 and the repeater selector 405,

and the previously mentioned circuit for energizing the left-hand winding of the answer relay R440. When the previouslymentioned loop circuit extending between the repeater 400 and the repeater selector 405 is thus interrupted, the answer relay R440 in the repeater 400 restores and the repeater selector 405 is released in order to effect the release of the party connector 4!. When the repeater selector 405 is thus released the application of ground potential is removed from the control conductor C583 of the trunk 400, thereby to interrupt the previously traced holding circuit for energizing in series the winding of the cutofii relay R330 and the rotary magnet M230 in the party line switch 320, in order to cause the latter relay to restore.

Upon restoring, the hold relay R400 interrupts, at the contacts 434, the previously traced circuit for energizing in series the upper and lower windings of the digit cutoff relay R4I0, thereby to cause the latter relay to restore. Also, upon restoring, the answer relay R440 interrupts; at the contacts 443, the previously traced circuit for energizing the meter M308 individually associated with the fourth party subscriber substation 304, connected to the party subscriber line I30. At this time the repeater 400 is completely released and is marked as idle to the party line switcheshaving access thereto by the absence of potential upon the control conductor C413 of the trunk 410.

' Upon restoring, the-cutoff relay R330 in the party line switch 320' interrupts, at the contacts 336, a further point in the previously traced circuit for energizing in series the winding of the cutofi relay R330 and the rotary magnet M326, and completes, at the contacts 331, an obvious circuit including the set of switch springs S354 and the contacts 353 for energizing the rotary magnet M352. At this point it is noted that the set-of switch springs S354 is actuated into engagement when the wiper 35I of the meter switch 350 is rotated inthe clockwise direction away from its home position. When thus energized therotary magnet M352 operates to interrupt, at the contacts 353, the previously traced circuit for energizing the rotary magnet M352, and to condition the wiper 35I to be driven an additional step in the clockwise direction. When the previously traced circuit for energizing the rotary magnet M352 is interrupted the latter ma net restores, thereby to recomplete, at the contacts 353, the circuit for energizing the rotary magnet M352 and to drive the wiper 35I one step in the clockwise direction away from its home position. In view of the foregoing explanation of the mode of operation of the rotary magnet M352, it will be understood that it is intermittently energized, thereby to drive the wiper 35I of the meter switch 350 step by step in the clockwise direction back into its home position. When the wiper 35I of the meter switch 350 is driven back into'its home position the set of switch springs S354 is actuated into disengagement, thereby to interrupt a further point in the previously traced circuit for energizing the rotary magnet M352 in order positively to arrest further operation thereof. At this time the meter switch 350 is completely released and restored to its normal position and the party line switch 320 is completely released. It is again noted that the wiper set of the party line switch 320 re.- mains in engagement with the contact set terminating the trunk 410 extending to the repeater 400, as the party line switch 320 is of the nonh min yp Also, when ground potential is removed from ntrol conductor G413 ofthe trunk 410, the

appl cation of round potential to the control 19 conductor CI33 of the party subscriber line I30 is interrupted, thereby to mark the last-men- 3H has replaced the receiver of the telephone instrument thereatupon its associated switchhook. Hence, the established connection between the calling fourth party subscriber substation 304, connected to the party subscriber line I30, and the called first party subscriber substation 3| I, connected to the party subscriber line I20, is completely released at this time.

In View of the foregoing explanation of the mode of operation of the apparatus incorporated in the telephone system to extend a connection from the calling fourth party subscriber substation 304, connected to the party subscriber line I30, to the called first party subscriber substation 3| I, connected to the party subscriber line I20, it will be understood that a call may be extended therefrom to thecalled second, third or fourth party subscriber substations 3I2, 3I3 'or 3, respectively, connected to the party subscriber line I20, in a substantially identical manner by dialing the appropriate directory number.

, As will be apparentfrom the trunking plan, the

directory numbers of the second, third and fourth party subscriber substations 3 I2, 3 I3 and 3I4, respectively, connected to the party subscriber line I20 are 3XX, 4XX and 5XX or 334, 434, and. 534, respectively, in accordance with the foregoing example. The party connectors 40I, 402, 403 and 404 respectively respond to the digits 1, 2, 3 and 4, in accordance with the foregoing example, to

seize the party subscriber line I and respecextended from the first, second or third party subscriber substations SM, 302 or 303, respectively, connected to the party subscriber line I30, to any one of the party subscriber substations 3I I, etc., connected to the party subscriber line I20,.in a manner substantially identical to that explained above. However, in the above-mentioned cases, when the calling devices at the respective first, second and third party subscriber substations 30I, 302 and 303, respectively, connected to the party subscriber line I30 are operated, no ground impulses, one ground impulse and two ground impulses are respectively transmitted therefrom in order to 'cause the corresponding operationsof the meter switch 350, whereby the meters M305, M306 and M30! respectively corresponding to the first, second and third party subscriber substations 30I, 302 and 303, respectively, are operated in order to register :the initiation of a call from the corresponding party subscriber substation.

Further, it will be understood that the extension of a call from one of the party subscriber substations, connected to a party subscriber line,

.to an individual subscriber substation, connected to an'individual subscriber line, is substantially the same as that described'above, whereby the appropriate meter is controlled in the manner previously explained; the above-mentioned connection is extended by way of one of the individual connectors. Also, it will be understood that the extension of a connection from an individual subscriber substation, connected to an individual subscriber line, to one of the party subscriber substations, connected to a party subscriber line, is substantially the same as that described above, whereby no metering is effected; the above-mentioned connection is extended by way of the appropriate one of the party connectors 40I etc. Finally, it is noted that the-:extension of a call from an individual subscriber substation, connected to an individual subscriber line, to an individual subscriber substation, connected to an individual subscriber line, is in accordance with conventional practice, whereby no metering is effected; the above-mentioned connection is extended by Way of one of the individual connectors.

Considering the extension of a call from a party subscriber substation, connected to a party subscriber line, such, for example, as the fourth party subscriber substation 304, connected to the party subscriber line I30, to the manual operator position 0, it is pointed out that the initiation and extension of the call from the calling fourth party subscriber substation 304 by way of the party line switch 320, the trunk 410, the repeater 400 and the trunk 480 to the repeater selector 405, are the same as that previously explained. At this time the subscriber at the calling fourth party subscriber substation 304 dials the'single digit 0, whereby the repeater selector 405 operates in order to seize an idle one of the trunks in the group extending to the manual operator position 0. The operator at the manual operator position 0 answers the 'call in accordance with conventional practice, whereby an established connection is completed between the calling fourth party subscriber substation 304, connected to the party subscriber line I30, and the called manual operator position 0. In connection with the extension of the above-mentioned call, it is noted that the operation of the meter relay R420 in the repeater 400 and the meter switch 350, incidental to the operation of the calling device I0 at the fourth party subscriber substation 304 to transmit the'digit 0, is the same as that previously explained. However, it is pointed out that the above-traced connection does not include a'connector. Accordingly, when the operator at the manual operatorposition 0 answers the call, battery potential is not reversed over the trunk 480 to the repeater 400.

Hence, the answer relay R440 in the repeater 400 does not operate in order to effect operation of the meter M308 individually associated with the calling fourth party subscriber substation 304, connected to the party subscriber lin I30, in view of the fact that the above-mentioned call is a free call which is not metered. Thus it will be understood that, although the meter switch 350 is set to select the meter M308 incidental to the dialing of the digit 0 upon the calling device I0 at the calling fourth party subscriber substation 304 to extend the above-mentioned call to the manual operator position 0, in the manner previously explained, the meter M308 is not operated to meter the call when the operator at the manual operator position 0 answers the call.

Considering now the extension of a call from 7 a party subscriber substation, connected to aparty subscriber line party subscriber line, such, for example, as the fourth party subscriber substation 3%, connected to the party subscriber line I39, to the toll operator position I I0, it is pointed out that the initiation and extension of the call from the calling fourth party subscriber substation 304 by way of the party line switch 32%, the trunk 4'10, the repeater 400 and the trunk 43%? to the repeater selector 405, are the same as that previously explained. At this time the subscriber at the calling fourth party subscriber substation 3M dials the directory number III), whereby the repeater selector 405 responds to the first digit 1 to select an idle special service selector, such, for example, as the special service selector 4%. The special service selector 406 responds to the second digit 1 and drops baclsin. a manner well understood, and then responds to the third digit to select an idle trunk to the toll operator position III). The operator at the toll operator position I I 0 answers the call in accordance with con- .ventional practice, whereby an established connectionis completed between the calling fourth party subscriber substation 304, connected to the I30, and the called toll operator position IIO. In connection with the extension of the above-mentioned call, it is noted that the operation of the meter relay R420 in the repeater 400 and the meter switch 350, incidental to the operation of the calling device ID at the fourth party subscriber substation 306 to transmit the first digit 1, is the same as that previously explained. However, it is pointed out that the above-traced connection does not include a connector. Accordingly, when the operator at the toll operator position I I0 answers the call, battery potential is not reversed over the trunk 480 to the repeater 400. Hence, the answer relay B44!) in the repeater 400 does not operate in order to efiect operation of the meter M391 individually associated with the calling third party subscriber substation 303, connected to the party subscriber line I30, in View of the fact that the above-mentioned call is a fre call which is not metered. Thus it will be understood that, although the meter switch 350 is set to select the meter M301 incidental to the dialing of the first digit 1 upon the calling device I!) at the calling fourth party subscriber substation 304 to extend the above-mentioned call to the toll operator position H0, in the manner previously explained, the meter M301 is not operated to meter the call when the operator at the toll operator position I Iii answers the call.

In connection with the extension of the abovementioned call, it is noted that incidental to the operation of the calling device III at the callin fourth party subscriber substation ace, connected to the party subscriber line I36, to transmit the first digit 1 to the line relay R458 in the repeater 409, this calling device I9 also sends two ground impulses to the meter relay R426 in the repeater 4120, thereby to cause the meter switch 35! to select the meter M30! individually associated with the third party subscriber substation 303 instead of the meter M308 individually associated with the calling fourth party subscriber substation 384 as previously noted. However, the selection of the improper meter M301 by the meter switch 359 in connec tion with the extension of the above-mentioned call is immaterial as the meter M301 is not operated, as explained above.

While there has been described what is at present considered to be the preferred embodimerit. of the invention, it will be understood that various modifications maybe made therein, and it is contemplated-tocover in the appended claims all such modifications as fall within the true spirit and scope of the'invention.

What is claimed is:

1. In a calling device, a dial having a normal position and being variably rotatable away therefrom to a plurality of other positions, an arbor operatively connected to said'dial, means for returning said dial back to its normal position after it has been rotated, a first cam operated through a gear train from said arbor only durin the returnof said dial, the rotation of said first cam depending upon the extent of the rotation of said dial, a first impulse sender comprising two springs-and having one spring en gageable by said first cam, a second impulse sender comprising two springs, a link between said one spring of said first impulse sender and one of the springsoi said second impulse sender causing said spring or said second impulse sender to directly follow the operation of said one spring engaged by said first cam, and a second cam operated by said arbor engageable with the other spring of said second impulse sender to advance said other spring into contact position, whereby said operating spring of the second impulse sender engages the advanced spring thereof to send a fixed number of impulses regardless of said other positions to which said dial has been operated.

2. In a calling device, a dial having a normal position and being variably rotatable away therefrom, an arbor operatively connected to said dial, means for returning said dial back to its normal position after it has been rotated, a first impulse sender, a first cam operated by said arbor only during the return of said dial, said first impulse sender operated by said first cam to send a variable number of impulses dependin upon the extent of the rotation of said dial, a second impulse sender, linkage means between said impulse senders, said linkage means operated by said first impulse sender to directly operate said second impulse sender, and a second cam mounted on said arbor and operable during the return of said dial to render said linkage means efiective or ineffective to operate said second impulse sender whereby said second impulse sender makes contact after and breaks contact before said first impulse sender, said second impulse sender making a fixed number of contacts regardless of the number of contacts made by said first impulse sender.

3. In a calling device, a dial having a normal position and being variably rotatable therefrom, an arbor operatively connected to said dial, means for returning said dial back to its normal position after it has been rotated, a first set of impulse springs, a first cam, means including a gear train operated from said arbor during the return of said dial for rotating said first cam, the extent of the rotation of said first cam depending upon the rotation of said dial, said first cam engaging one of said first set of impulse springs, a second set of impulse springs, a link between the cam engaging spring of said first set of impulse springs and one of said second set of impulse springs thereby causing said one spring of said second set of impulse springs to follow the movement of said first cam engaged spring, and means including a pawl and a second cam mechanism disposed between said arbor and said second set of impulse springs and op- I erated during the return of said dial for advancing the other of said second set of impulse springs into contact position whereby said linked spring "of said second set of impulse springs makes contact with the advanced spring thereof after and breaks contact before said first impulse springs during the time that the other of said second set of impulse springs is advanced by said second cam.

4. In a calling device, a dial havin a normal position and being variably rotatable away therefrom, an arbor operatively connected to said dial, means for returning said dial back to its normal position after it has been rotated, a

'firstset of impulse springs, a first cam, means -including a gear train operated from said arbor during the return of said dial for rotating said first cam, the extent of the rotation of said first cam depending upon the extent of the rotation causes the operation of said other linked spring,

a second cam operable to advance the other of said second set of impulse springs into a position where it can contact its linked spring when said linked spring is operated by said linked spring of said first set of impulse springs so that said second set of impulse springs can make and break contact only during the time said first set of impulse springs can make and break contact, the number of impulses sent by said second set of impulse springs depending upon the extent of advancement of said other of said second set of impulse springs by said second cam.

LEN B. MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,969,926 Eichoff -i Aug. 14, 1934 2,043,674 Obergfell June 9, 1936 2,320,401 Beizer June 1, 1943 2,366,647 Ostline Jan. 2, 1945 

